1. Field of the Invention
The present invention relates to a lens barrel and a lens barrel system to which a lens barrel external attachment member can be detachably mounted.
2. Related Art Statement
Heretofore, there are various proposals as to a protection structure for protecting a lens barrel against shock force due to drop and the like. A proposal disclosed in Japanese Unexamined Patent Application Publication No. 8-160277 relates to a lens barrel having a moving ring, which is supported in a fixed cylinder so as to move forward and rearward therein for holding a variable lens, and a cam cylinder for moving the moving ring forward and rearward. A roller (cam follower) is disposed to the outer periphery of the moving ring so that it can be slidably inserted into a cam groove formed to the fixed cylinder and the cam cylinder. The roller is attached to the moving ring through an elastically deformable sheet member. Accordingly, when shock force acts on the moving ring due to drop and the like, the shock force is absorbed by the sheet member being elastically deformed, thereby the roller is prevented from being removed from the cam groove, and the cam groove is prevented from being damaged.
Further, a proposal disclosed in Japanese Unexamined Patent Application Publication No. 9-211286 relates to a lens barrel in which a plurality of slots are formed along the peripheral direction of a synthetic resin cylindrical member mounted to the extreme end portion of the lens barrel. The slots have such a shape that they can be elastically deformed in the axis direction of the cylindrical member, and projections are formed to front positions of the slots. Further, a filter frame for mounting a filter is inserted into the extreme end of the cylindrical member so that the projections are abutted against the filter frame. In the lens barrel, when shock force acts on the filter frame due to drop and the like, the slots are elastically deformed through the projections so as to absorb the shock force. Accordingly, the cylindrical member or incorporated parts coupled with the cylindrical member can be prevented from being deformed and damaged.